Fuel and engine oil composition and its use

ABSTRACT

A composition is provided that contains a major amount of a hydrocarbon base fluid having a viscosity of up to 600 cST at 40 ° C. and (b) a minor amount of a micronized cellulose acetate butyrate having a particle size distribution on average of less than 30 microns. The compositions reduce and control the friction coefficient and anti-wear film of hydrocarbon base fluids.

The present application claims the benefit of U.S. patent application Ser. No. 61/665,003, filed Jun. 27, 2012 the entire disclosure of which is hereby incorporated by reference.

FIELD OF THE INVENTION

The present invention relates to fuel and engine oil compositions and their use, particularly, in combustion engines.

BACKGROUND OF THE INVENTION

Engine manufactures in developed countries are continuously challenged to improve the fuel economy of vehicles in the market place. The original equipment manufacturers for vehicles are being pressured to meet and exceed the Environmental Protection Agency's Corporate Average Fuel Economy (CAFE) requirements as well to reduce the vehicles fuel consumption, which in turn would reduce the dependency on imported oil. CAFE is the sales weighted average fuel economy, expressed in miles per gallon (mpg), of a manufacturer's fleet of passenger cars or light trucks with a gross vehicle weight rating (GVWR) of 8,500 lbs. or less, manufactured for sale in the United States, for any given model year. Fuel economy is defined as the average mileage traveled by an automobile per gallon of gasoline (or equivalent amount of other fuel) consumed as measured in accordance with the testing and evaluation protocol set forth by the Environmental Protection Agency (EPA).

A vehicle fuel economy improvement can be accomplished in many ways. However, it is believed that one major area is friction. Engine friction can be separated into six areas with each area contributing to a certain amount of frictional losses. The approximate area of contribution to engine friction are: 6.0% valve train, 25% piston, 19% rings, 10% connecting rod bearings, 12.5% main bearings, 27.5% pump loss.

Friction modifier such as isohexyloxyproplyamine isostearate or cyclic saturated carboxylic acid salts of an alkoxylated amine or ether amines, which are reported in U.S. Pat. No. 7,435,272, are currently used as friction modifiers in fuel. However, to meet the requirements of ever demanding fuel economy vehicle, it is desirable to provide fuels and motor oils with more efficient friction modification.

Modern engine lubricating oil is a complex, highly engineered mixture, up to 20 percent of which may be special additives to enhance properties such as viscosity and stability and to reduce sludge formation and engine wear. For years antiwear additives for high-performance oils such as zinc dialkyldithiophosphate (ZDDP) has been used that work by forming a protective Zinc polyphosphate film on engine parts that reduces wear. This film, referred to as a tribofilm or antiwear film, becomes harder and more glassy in nature as the engine is operated.

SUMMARY OF THE INVENTION

Therefore it is desirable to obtain fuels and lubricants with efficient friction modification to meet the modern engine needs.

In accordance with certain of its aspects, in one embodiment of the present invention provides a composition comprising: (a) a major amount of a hydrocarbon base fluid having a viscosity of up to 600 cST at 40° C. and (b) a minor amount of a micronized cellulose acetate butyrate having a butyrate content in the range of 20 to 60 wt %, based on hydroxyl equivalent of the polymer and a number average molecular weight in the range from about 5,000 to about 50,000, and a particle size distribution on average of less than 30 microns.

In another embodiment, the present invention provides a fuel composition comprising: (a) a major amount of a hydrocarbon base fluid having a viscosity of up to 600 cST at 40° C. and (b) a minor amount of a micronized cellulose acetate butyrate having a butyrate content in the range of 20 to 60 wt %, based on hydroxyl equivalent of the polymer and a number average molecular weight in the range from about 5,000 to about 50,000, and a particle size distribution on average of less than 30 microns.

In another embodiment, the present invention provides a lubricating oil composition comprising (a) a major amount of mineral and/or synthetic base oil having a viscosity of up to 600 cST at 40° C. and (b) a minor amount of a micronized cellulose acetate butyrate having a butyrate content in the range of 20 to 60 wt %, based on hydroxyl equivalent of the polymer and a number average molecular weight in the range from about 5,000 to about 50,000, and a particle size distribution on average of less than 30 microns.

Yet in another embodiment, the present invention provides a method for reducing friction coefficient or wear in antiwear film in an internal combustion engine which comprises burning in said engine a fuel composition described above.

Yet in another embodiment, the present invention provides a method for preparing such micronized cellulose acetate butyrate having a butyrate content in the range of 20 to 60 wt %, based on hydroxyl equivalent of the polymer and a number average molecular weight in the range from about 5,000 to about 50,000, and a particle size distribution on average of less than 30 microns.

In another embodiment, the present invention provides a micronized polymer of a cellulose acetate butyrate having a butyrate content in the range of 20 to 60 wt %, based on hydroxyl equivalent of the polymer and a number average molecular weight in the range from about 5,000 to about 50,000, and a particle size distribution on average of less than 30 microns

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 represents the HFRR wear scar results of cellulose acetate butyrate polymers and micronized cellulose acetate butyrate polymers.

DETAILED DESCRIPTION OF THE INVENTION

We have found that a hydrocarbon fluid composition comprising: (a) a major amount of a hydrocarbon base fluid having a viscosity of up to 600 cST at 40° C. and (b) a minor amount of a micronized cellulose acetate butyrate having a butyrate content in the range of 20 to 60 wt %, based on hydroxyl equivalent of the polymer and a number average molecular weight in the range from about 5,000 to about 50,000, and a particle size distribution on average of less than 30 microns provide excellent boundary friction value and improves the response of the antiwear film to the micronized cellulose acetate butyrate.

A friction modifier works by absorbing its polar end toward the metal surface allowing the two moving metal surfaces to slide over each other easily. Therefore if a friction modifier is able to emulsify with water, which may come in contact with the fuel, the friction modifier becomes an emulsifier and as a consequence may not be attached to the metal surface. In addition if a friction modifier is capable of emulsifying with water and is formulated into a fuel additive package; the emulsifier which is part of the fuel additive package may need to be increased to compensate for the added emulsibility/loss of the friction modifier because any water which may be dispersed in the fuel could cause engine problems such as stalling, hesitation or complete engine failure. Therefore it would be advantageous to develop a friction modifier which is able to reduce friction but also able to enhance antiwear films but not emulsify water and in fact separate the water from the fuel. We have found that micronized cellulose acetate butyrate can provide excellent friction modification and antiwear properties even for used/oxidized motor oil as well as fresh motor oil.

Commercial cellulose acetate butyrate typically has an average particle size of 300 microns or larger. Any cellulose acetate butyrate can be subjected to the method of the invention to produce the micronized cellulose acetate butyrate. Thus, the cellulose acetate butyrate can be any cellulose acetate butyrate having a particle size of greater than 30 micron, even greater than 50 microns, or an average particle size of 100 microns or greater to a typical commercial cellulose acetate butyrate. Cellulose acetate butyrate is commercially available from Sigma-Aldrich Co. LLC, Alpha Chem Corporation, Eastman Chemical Company, and other suppliers.

Cellulose acetate butyrate has a general structure of:

wherein n is number so as to provide the number average molecular weight of the polymer. The cellulose acetate butyrate suitable for use preferably have a butyrate content of 20 to 60 wt %, more preferably 30 to 55 wt %, based on hydroxyl equivalents in the polymer. In an embodiment, the hydroxyl content of the cellulose acetate butyrate is preferably less than 10 wt % , preferably less than 5 wt %, based on the entire polymer.

It has been found by micronizing the cellulose acetate butyrate to an average particle size less than 30 microns, preferably less than 25 microns, more preferably less than 20 microns, most preferably less than 15 microns, the micronized cellulose acetate butyrate provides a reduction in the lubricants friction coefficient and anti-wear film. The term “micronized cellulose acetate butyrate” means cellulose acetate butyrate that has been treated so that the average particle size less than 30 microns. Typically, the micronized cellulose acetate butyrate particle size distribution is between 0.1-30 microns, with preferably having an average particle size in the range of about 0.5 to 25 micron. Suitable cellulose acetate butyrate typically have a number average molecular weight of at least 5000, preferably at least 6000, more preferably at least 8000, to at most 50,000, preferably to at most 40,000, more preferably to at most 30,000.

Micronized cellulose acetate butyrate can be prepared by subjecting cellulose acetate butyrate to molecular segmentation. A process where polymer aggregates are de-entangled via processing is referred to as “Molecular Segmentation”. Molecular Segmentation is a process which increases the critical entropy energy of the polymer aggregate by intrapenetrating the polymer aggregate matrix and generating/developing a simpler singular Cellulose acetate butyrate polymer. This process generates a smaller particle size without degrading the polymers molecular weight. Molecular Segmentation can be generated in a number of ways such as thermally, vibrationally or chemically to name a few.

Examples of methods that can be used for molecular segmentation include spray drying, microfluidization, sonification, pan coating, air suspension coating, centrifugal extrusion, vibrational nozzle, ionotropic gelation, coacervation, interfacial polycondensation, interfacial crosslinking, in-situ polymerization, electrospinning and matrix polymerization

The hydrocarbon fluid blend can be prepared by: (a) providing a micronized cellulose acetate butyrate having a butyrate content in the range of 20 to 60 wt %, based on hydroxyl equivalent of the polymer and a number average molecular weight in the range from about 5,000 to about 50,000 having a particle side distribution of greater than 30 microns, in a polar organic solvent in a polymer to solvent ratio of 1:1 to 1:10 to provide a polymer-containing solution. Preferably, the polar organic solvent is non-flammable, such as for example, dichloromethane. Polar organic solvents such as ethanol, tetrahydrofuran, ethyl acetate, methanol and halogenated paraffins may also be used. The polymer solution is subjected to molecular segmentation to produce a micronized polymer having a particle size distribution of less than 30 microns. The micronized polymer is blended with a hydrocarbon fluid to produce a solubilized and/or dispersed hydrocarbon fluid blend. Depending on the solvent used, the solvent may be removed from the micronized polymer.

By such method, a micronized polymer of a cellulose acetate butyrate having a butyrate content in the range of 20 to 60 wt %, based on hydroxyl equivalent of the polymer and a number average molecular weight in the range from about 5,000 to about 50,000, and a particle size distribution on average of less than 30 microns useful in hydrocarbon fluids may be produced. The molecular weight of the polymer is substantially unchanged, less than 6%, from the non-micronized polymer, where as the particle size is reduced.

The particle size distribution is given herein by the Sauter mean diameter. The Sauter mean diameter is a measure of the mean particle size per unit surface area. The Sauter mean diameter (also noted as D₃₂) may be calculated from the surface area (A_(p)) and volume (V_(p)) of a particle, according to the formula:

D ₃₂=6*(V _(p)/A _(p))

An effective amount of micronized cellulose acetate butyrate is introduced into the combustion zone of the engine in a variety of ways to reduce the friction between the piston ring and the cylinder wall. As mentioned, a preferred method is to add a minor amount micronized cellulose acetate butyrate to the fuel or lubricant. For example, micronized cellulose acetate butyrate may be added directly to the motor oil or fuel or blended with one or more carriers and/or one or more additional detergents to form an additive concentrate which may then be added at a later date to the fuel.

Generally, micronized cellulose acetate butyrate is added in an amount up to about 5% by weight, especially from about 0.05% by weight, more preferably from about 0.1% by weight, even more preferably from about 0.5% by weight, to preferably about 4% by weight, more preferably to about 2% by weight, based on the total weight of the hydrocarbon fluid. The term “minor amount” is used herein because the amount of micronized cellulose acetate butyrate is added in an amount that is less than the amount of hydrocarbon base fluid.

Suitable hydrocarbon base fluid typically comprise mixtures of saturated hydrocarbons, olefinic hydrocarbons and aromatic hydrocarbons and have a viscosity of up to 600 cST at 40° C., preferably in the range of 1 to 600 cSt at 40° C. Further details of the hydrocarbon base fluid is provided below in fuel composition and lubricating oil composition. The term “major amount” is used herein because the amount of hydrocarbon base fluid is often about 50 weight or volume percent or more, preferably 80 weight or volume percent or more.

It was found that micronized CAB polymer enhances dispersibility and stability compared to non-micronized CAB polymers. As such hydrocarbon fluids, such as fuels and lubricants, containing higher amounts of the micronized CAB polymer dispersed in the hydrocarbon fluids may be obtained. The primary method used to assess dispersion stability is zeta potential. The zeta potential is the potential difference between the dispersing medium and the stationary layer of fluid interacting with the dispersed particle. The significance of zeta potential is that this value can be related to the stability of colloidal dispersions. The zeta potential indicates the degree of repulsion between adjacent, similarly charged particles in a dispersion. Colloids with high zeta potentials are either electrically or sterically stabilized, and will resist aggregation, while colloids with low zeta potentials will coagulate or flocculate. This is especially important in fuel and lubricant applications, as polar polymers are not soluble in these media. Therefore, micronization may be employed to improve the stability of adding these materials to fuels and lubricants, and the degree of improvement may be monitored by zeta potential.

Fuel Composition

The hydrocarbon fluid useful in the fuel composition may be any base fuel used or may be useful for fuel composition.

It has been found that a fuel containing (a) a major amount of a mixture of hydrocarbons in the gasoline boiling range and having a viscosity of up to 600 cST at 40 ° C. and (b). a minor amount of a micronized cellulose acetate butyrate having a particle size distribution on average less than 30 microns provides reduced wear scar values.

Preferably, in a fuel composition micronized cellulose acetate butyrate is added in an amount up to about 1% by weight, especially from about 0.05% by weight, more preferably from about 0.1% by weight, even more preferably from about 0.5% by weight, based on the total weight of the hydrocarbon fluid.

The fuel compositions of the present invention may in addition to the micronized cellulose acetate butyrate contain one or more additional additives such as detergents. When additional additives are utilized, the fuel composition will comprise a mixture of a major amount of hydrocarbons in the gasoline boiling range as described hereinbefore, a minor amount of micronized cellulose acetate butyrate as described hereinbefore and a minor amount of one or more additional additives. As noted above, a carrier as described hereinbefore may also be included. As used herein, the term “minor amount” means less than about 10% by weight of the total fuel composition, preferably less than about 1% by weight of the total fuel composition and more preferably less than about 0.1% by weight of the total fuel composition. However, the term “minor amount” will contain at least some amount, preferably at least 0.001%, more preferably at least 0.01% by weight of the total fuel composition.

The one or more additional detergents are added directly to the hydrocarbons, blended with one or more carriers, blended with micronized cellulose acetate butyrate, or blended with micronized cellulose acetate butyrate and one or more carriers before being added to the hydrocarbon. The micronized cellulose acetate butyrate can be added at the refinery, at a terminal, at retail, or by the consumer.

For gasoline composition, preferred hydrocarbon base fluid are gasoline mixtures having a saturated hydrocarbon content ranging from about 40% to about 80% by volume, an olefinic hydrocarbon content from 0% to about 30% by volume and an aromatic hydrocarbon content from about 10% to about 60% by volume. Such base fluid can be derived from straight run gasoline, polymer gasoline, natural gasoline, dimer and trimerized olefins, synthetically produced aromatic hydrocarbon mixtures, or from catalytically cracked or thermally cracked petroleum stocks, and mixtures. The hydrocarbon composition and octane level of the base fluid are not critical. The octane level, (R+M)/2, will generally be above about 83 for fuel composition. The United States gasoline specification for the hydrocarbon base fluid (a) in the gasoline composition which is preferred has the following physical properties and can be seen in Table 1.

TABLE I US Gasoline Physical Properties Properties Units Min Max Vapor Pressure psi 6.4 15.0 Distillation (° F./Evap) vol % 10% 122 158 50% 150 250 90% 210 365 EP 230 437 Drivability Index* 1050 1250 *DI = 1.5(T10) + 3.0 (T50) + 2.4 (ETOH vol %)

The gasoline specification D 4814 controls the volatility of gasoline by setting limits for the vapor pressure, distillation, drivability index and the fuels end point.

The European Union gasoline specification for the hydrocarbon base fluid (a) in the gasoline composition in which is preferred has the following physical properties which are shown in Table 2.

TABLE 2 European Gasoline Specification Properties Units Min Max Vapor Pressure Kpa 45.0 90.0 % Evap at Vol %  70° C. 20 50 100° C. 46 71 150° C. 75 FP 210 Distillation Residue 2 VLI (10 VP_(psi) + 7 E70) 1050 1250

Hydrocarbons in the gasoline can be replaced by up to a substantial amount of conventional alcohols or ethers, conventionally known for use in fuels. The base fluids are desirably substantially free of water since water could impede a smooth combustion.

Normally, the hydrocarbon fuel mixtures to which the invention is applied are substantially lead-free, but may contain minor amounts of blending agents such as methanol, ethanol, ethyl tertiary butyl ether, methyl tertiary butyl ether, tert-amyl methyl ether and the like, at from about 0.1% by volume to about 17% by volume of the base fuel, although larger amounts may be utilized. The fuels can also contain conventional additives including antioxidants such as phenolics, e.g., 2,6-di-tertbutylphenol or phenylenediamines, e.g., N,N′-di-sec-butyl-p-phenylenediamine, dyes, metal deactivators, dehazers such as polyester-type ethoxylated alkylphenol-formaldehyde resins. Corrosion inhibitors, such as a polyhydric alcohol ester of a succinic acid derivative having on at least one of its alpha-carbon atoms an unsubstantiated or substituted aliphatic hydrocarbon group having from 20 to 50 carbon atoms, for example, pentaerythritol diester of polyisobutylene-substituted succinic acid, the polyisobutylene group having an average molecular weight of about 950, in an amount from about 1 ppm (parts per million) by weight to about 1000 ppm by weight, may also be present.

The treat rate of the fuel additive packages that may contain one or more additional additives in the final fuel composition is generally in the range of from about 0.007 weight percent to about 0.76 weight percent based on the final fuel composition. The fuel additive package may contain one or more detergents, dehazer, corrosion inhibitor and solvent. In addition a carrier fluidizer may sometimes be added to help in preventing intake valve sticking at low temperature. Therefore a gasoline additive composition may contain any one or more of the following combinations: Detergent, Carrier Fluid, Dehazer, Corrosion Inhibitor, and Solvent. Examples of additives suitable for gasoline fuel are described in U.S. Pat. No. 5,855,629, which disclosure is hereby incorporated by reference.

For Diesel composition, preferred hydrocarbon base fluids are mixtures having a carbon ranging between C₁₀-C₂₀. Diesel fuel produced by a refinery is a blend of various streams. These streams composed of straight-run, FCC light cycle oil, and hydrocracked gas oil. The refiner must blend the available streams to meet all performance, regulatory, economic, and inventory requirements. The refiner really has limited control over the composition of the final diesel blend. The final blend is determined primarily by the composition of the crude oil feed, which is usually selected based on considerations of availability and cost. The diesel composition and cetane level of the base fluid are not critical. The cetane level will generally be above about 40 but could be as low as 30 for fuel composition. The hydrocarbon base fluid (a) for diesel fuel composition must meet either US ASTM 975 or Europe's EN 590 specifications.

The preferred United States Diesel Fuel physical properties for the hydrocarbon base fluid (a) in the diesel composition can be seen in Table 3.

TABLE 3 US Requirements for Diesel Fuel Oils Diesel Property Method Min Max Flash Point, ° F. D 93 100 130 Water and Sediment, vol %, max D2709/D1796 0.05 Distillation ° F. D86 90% ° F. min 540 640 Kin Viscosity, 40° C., cST D445 1.3 5.5 Ash, max % D482 0.01 Sulfur, (ppm, max) D5453 Diesel # 1 15 Diesel # 2 15 wt % D2622 Diesel # 1 0.05 Diesel # 2 0.05 wt % D129 2.0 Diesel # 1 0.5 Diesel # 2 0.5 Diesel # 4 2.0 Copper Strip, max D130 Diesel # 1 #3 Diesel # 2 #3 Diesel # 4 #3 Cetane Number, min D613 Diesel # 1 and 2 40 Diesel # 4 30 Cetane Index D976-80 40 Aromaticity, vol % max D1319 35 Ramsbottom Carbon Residue, max D524 Diesel # 1 0.15 Diesel # 2 0.35 Lubricity 60° C. WSD, microns, max D6079 520 Diesel # 1 Diesel The European preferred Diesel Fuel physical properties for the hydrocarbon base fluid (a) in the diesel composition can be seen in Table 4.

TABLE 4 European Diesel Fuel Specification Specification Test Method Units Limits Cetane Number EN ISO 5165 51 min Cetane Index EN ISO 4264 46 min Density at 15° C. EN ISO 3675, min kg/m³ 820 EN ISO 12185 kg/m³ 845 Polycyclic Aromatization EN 12916 % (m/m) 11 Hydrocarbons Sulfur EN ISO 20846 mg/kg 50 max 20847 10 max 20884 Flash Point EN ISO 2719 ° C.

 55 Carbon Residue (on 10% EN ISO 10370 % (m/m) 0.30 max dist. Residue) Ash Content EN ISO 6245 % (m/m) 0.01 max Water Content EN ISO 12937 mg/kg 200 max Total Contamination EN ISO 12662 mg/kg 24 max Copper Strip Corrosion EN ISO 2160 3 hours Class 1 at 50° C. Oxidative Stability EN ISO 12205 g/m³ 25 max Lubricity, WSD at 60° C. EN ISO 12156-1 Um 460 max Vis at 40° C. EN ISOO104 cST 2.0 min 4.5 max Distillation EN ISO 3405 (vol recovered) 250° C. % V/V <65 350° C. % V/V 85 min 95% Point ° C. 360 max Fatty Acid Methyl Esters EN 14078 % V/V 5 max (FAME) content

The Diesel fuel compositions of the present invention may also contain one or more additional additives such as detergents. When additional additives are utilized, the fuel composition will comprise a mixture of a major amount of hydrocarbons in the diesel boiling range as described hereinbefore, a minor amount of micronized cellulose acetate butyrate as described hereinbefore and a minor amount of one or more additional additives. The treat rate of the fuel additive packages that contains one or more additional additives in the final fuel composition is generally in the range of from about 0.007 weight percent to about 0.76 weight percent based on the final fuel composition. The fuel additive package may contain one or more detergents, dehazer, corrosion inhibitor and solvent.

Therefore a diesel additive composition may contain any one or more of the following combinations: Detergent, Carrier Fluid, Dehazer, Corrosion Inhibitor, Solvent, Anti-oxidant, De-icer lubricity improver, Cold Flow improver, and Cetane improver. Examples of additives suitable for diesel fuel are described in US2007/0187293, which disclosure is hereby incorporated by reference.

Lubricant Oil Composition

The base oil used in the lubricating oil compositions in the present invention may comprise any mineral oil, any synthetic oil or mixtures thereof and have a viscosity of up to 600 cST at 40° C., preferably in the range of 1 to 600 cSt at 40° C.

Generally in a lubricating oil composition, micronized cellulose acetate butyrate is added in an amount up to about 5% by weight, especially from about 0.05% by weight, more preferably from about 0.1% by weight, even more preferably from about 0.5% by weight, to preferably to about 4% by weight, more preferably to about 2% by weight, based on the total weight of the hydrocarbon fluid.

Base oils of mineral origin may include those produced by solvent refining or hydro processing.

Mineral oils that may be conveniently used include paraffinic oils or naphthenic oils or normal paraffins, for example, those produced by refining lubricating oil cuts obtained by low-pressure distillation of atmospheric residual oils, which were in turn obtained, by atmospheric distillation of crude oil.

Examples of mineral oils that may conveniently be used include those sold by member companies of the Royal Dutch/Shell Group under the designations “HVI”, “MVIN”, or “HMVIP”.

Specific examples of synthetic oils that may be conveniently used include polyolefin's such as poly-α-olefins, co-oligomers of ethylene and α-olefins and polybutenes, poly(alkylene glycol)s such as poly(ethylene glycol) and poly(propylene glycol), diesters such as di-2-ethylhexyl sebacate and di-2-ethylhexyl adipate, polyol esters such as trimethylolpropane esters and pentaerythritol esters, perfluoroalkyl ethers, silicone oils and polyphenyl ethers. Such synthetic oils may be conveniently used as single oils or as mixed oils.

Base oils of the type manufactured by the hydroisomerization of wax, such as those sold by member companies of the Royal Dutch/Shell Group under the designation “XHVI” (trade mark), may also be used.

The micronized cellulose acetate butyrate may be added to the base oil, but may also be added to other additives then added to the base oil or added at the same time as other additives.

In addition to the micronized cellulose acetate butyrate, the lubricant oils may also contain a number of conventional additives in amounts required to provide various functions. These additives include, but are not limited to, ashless dispersants, metal or overbased metal detergent additives, anti-wear additives, viscosity index improvers, antioxidants, rust inhibitors, pour point depressants, friction reducing additives, and the like.

Suitable ashless dispersants may include, but are not limited to, polyalkenyl or borated polyalkenyl succinimide where the alkenyl group is derived from a C₃-C₄ olefin, especially polyisobutenyl having a number average molecular weight of about 5,000 to 7,090. Other well known dispersants include the oil soluble polyol esters of hydrocarbon substituted succinic anhydride, e.g. polyisobutenyl succinic anhydride, and the oil soluble oxazoline and lactone oxazoline dispersants derived from hydrocarbon substituted succinic anhydride and di-substituted amino alcohols. Lubricating oils typically contain about 0.5 to about 5 wt % of ashless dispersant.

Suitable metal detergent additives are known in the art and may include one or more of overbased oil-soluble calcium, magnesium and barium phenates, sulfurized phenates, and sulfonates (especially the sulfonates of C₁₆-0₅₀ alkyl substituted benzene or toluene sulfonic acids which have a total base number of about 80 to 300). These overbased materials may be used as the sole metal detergent additive or in combination with the same additives in the neutral form; but the overall metal detergent additive should have a basicity as represented by the foregoing total base number. Preferably they are present in amounts of from about 3 to 6 wt % with a mixture of overbased magnesium sulfurized phenate and neutral calcium sulfurized phenate (obtained from C₉ or C₁₂ alkyl phenols).

Suitable anti-wear additives include, but are not limited to, oil-soluble zinc dihydrocarbyldithiophosphates with a total of at least 5 carbon atoms and are typically used in amounts of about 1-6% by weight.

Suitable viscosity index improvers, or viscosity modifiers, include, but are not limited to olefin polymers, such as polybutene, hydrogenated polymers and copolymers and terpolymers of styrene with isoprene and/or butadiene, polymers of alkyl acrylates or alkyl methacrylates, copolymers of alkyl methacrylates with N-vinyl pyrrolidone or dimethylaminoalkyl methacrylate, post-grafted polymers of ethylene and propylene with an active monomer such as maleic anhydride which may be further reacted with alcohol or an alkylene polyamine, styrene-maleic anhydride polymers post-reacted with alcohols and amines and the like. These are used as required to provide the viscosity range desired in the finished oil in accordance with known formulating techniques.

Examples of suitable oxidation inhibitors include, but are not limited to hindered phenols, such as 2,6-di-tertiarybutyl-paracresol, amines sulfurized phenols and alkyl phenothiazones. Usually, lubricating oil may contain about 0.01 to 3 wt % of oxidation inhibitor, depending on its effectiveness. For improved oxidation resistance and odor control, it has been observed that up to about 5 wt % of an antioxidant should be included in the aforementioned formula. One suitable example of such, butylated hydroxytoluene (“BHT”), or di-t-butyl-p-cresol, is sold by many supplies including Rhein Chemie and PMX Specialties. Another suitable example is Irganox L-64 from Ciba Geigy Corp.

Rust inhibitors may be employed in very small proportions such as about 0.1 to 1 weight percent with suitable rust inhibitors being exemplified by C₉-C₃₀ aliphatic succinic acids or anhydrides such as dodecenyl succinic anhydride. Antifoam agents are typically included, but not limited to polysiloxane silicone polymers present in amounts of about 0.01 to 1 wt %.

Pour point depressants are used generally in amounts of from about 0.01 to about 10.0 Wt %, more typically from about 0.1 to about 1 wt %, for most mineral oil base stocks of lubricating viscosity. Illustrative of pour point depressants which are normally used in lubricating oil compositions include, but are not limited to, polymers and copolymers of n-alkyl methacrylate and n-alkyl acrylates, copolymers of di-n-alkyl fumarate and vinyl acetate, alpha-olefin copolymers, alkylated naphthalenes, copolymers or terpolymers of alpha-olefins and styrene and/or alkyl styrene, styrene dialkyl maleic copolymers and the like.

As discussed in U.S. Pat. No. 6,245,719, which disclosure is incorporated by reference herein, a variety of additives may be used to improve oxidation stability and serviceability of lubricants used in automotive, aviation, and industrial applications. These additives include calcium phenate, magnesium sulfonate and alkenyl succinimide to agglomerate solid impurities, a combination of an ashless dispersant, metallic detergent and the like, an oxidation inhibitor of sulfur-containing phenol derivative or the like, an oxidation inhibitor or the like, or mixtures thereof. Therefore a lubricant composition may contain any one or more of the following combinations

Base Oil, Micronized Cellulose acetate butyrate, Viscosity Modifier, Pour Point Improver, Additives such as Detergent, Dispersant, Anti-oxidant, Anti-wear, Friction Modifier, Anti-foam, Demulsifiers, Emulsifiers, Rust Inhibitors, Corrosion Inhibitors, Seal Compatibility, Tackifier, Antimist, Biocides, and Dye.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of examples herein described in detail. It should be understood, that the detailed description thereto are not intended to limit the invention to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the present invention as defined by the appended claims. The present invention will be illustrated by the following illustrative embodiment, which is provided for illustration only and is not to be construed as limiting the claimed invention in any way.

Illustrative Embodiment Test Methods

Average Particle Size

A Malvern Masterxizer 2000 outfitted with a Sirocco dry powder accessory was used for the determination of average particle size. An adequate amount of sample is placed within the Sirocco accessory, and the material is then fed into the measuring unit ( Mastersizer 2000) using an ultrasonics setting of approximately 50% (to provide a reasonable material feed rate). The critical parameter to be adjusted during this measurement is the air pressure. Since water-soluble polymers absorb moisture well, they often agglomerate easily when not dispersed in a solvent. Therefore, air is used to assist in breaking up these agglomerations. The air pressure is titrated to provide the best measurement conditions. To compare micronized polymer with the commercial starting material, the Sauter mean diameter is used and determined in ethanol.

Density (ASTM D70)

The density of the solid was measured using a calibrated pycnometer. The pycnometer and sample are weighed, then the remaining volume is filled with helium The filled pycnometer is brought to ambient temperature (25° C./77° F.), weighed. The density of the sample is calculated from its mass and the mass of helium displaced by the sample in the filled pycnometer.

Viscosity (ASTM D-445)

The kinematic viscosity of the micronized polymer was measured according to the ASTM method by dissolving 1wt % of the micronized polymer in DCM (dichloromethane)/ETOH (Ethanol) solution—84/16 vol % solution.

Zeta Potential

The Malvern Nano-Z is designed to measure zeta potential using laser light scattering. The process involves placing a sample of appropriate concentration (0.1% to 15%, depending on the light absorbance characteristics of the material) in a “dip cell”, which consists of a cuvette equipped with electrodes to place a potential across the sample. The instrument is automated with respect to the measurement process, and self-adjusts the settings to optimize the results. The zeta potential was measured in water.

High Frequency Reciprocating Rig

This test method covers the evaluation of the lubricity of Gasoline and Diesel fuels using a high-frequency reciprocating rig (HERR). A 2-mL test specimen of fuel is placed in the test reservoir of an HERR and adjusted to either of the temperatures (25 or 60° C). If diesel was going to be evaluated the temperature would be 60° C.; however if gasoline was going to be evaluated, the temperature would be 25° C.

When the fuel temperature has stabilized, a vibrator arm holding a non-rotating steel ball and loaded with a 200-g mass is lowered until it contacts a test disk completely submerged in the fuel. The ball is caused to rub against the disk with a 1-mmstroke at a frequency of 50 Hz for 75 min. The ball is removed from the vibrator arm and cleaned. The dimensions of the major and minor axes of the wear scar are measured under 1003 magnification and recorded.

The HFRR test condition is the following:

Fluid Volume 2 +/− 0.2 ml Stroke Length 1 +/− 0.02 mm Frequency 50 +/− 1 Hz Fluid Temperature 25 +/− 2° C. Relative Humidity >30% Applied Load 200 +/− 1 g Test duration 75 +/− 0.1 min Bath Surface area 6 +/− cm²

EXAMPLES

Fuel

The base fuel used in the test was an 82 R+M/2 regular base fuel for the fuel composition. The base fuel physical properties can be found in Table 5.

TABLE 5 Base Fuel Physical Properties API Gravity 54.5 RVP 5.38 Distillation, (° F.) IBP 106.5 10% 142.8 20% 176.2 30% 192.4 40% 209.5 50% 228.3 60% 250.8 70% 278.8 80% 309.5 90% 343.1 95% 366.6 End Pt. 415.1 % Recovered 97.2 % Residue 1.0 % Loss 1.8 FIA (vol %) Aromatic 28.6 Olefins 9.7 Saturates 61.7 Gum (mg/100 ml) Unwashed 17 MON 79.0 RON 85.0 R + M/2 82.0 Oxygenates None

Example 1

Micronizing Cellulose acetate butyrate by molecular segmentation processes

Spray Dry Method

Micronized cellulose acetate butyrates were prepared using cellulose acetate butyrate (CAB) obtained from Sigma-Aldrich Co. LLC having a number average molecular weight of approximately 30,000 and a butyrate content of approximately 52. The micronized cellulose acetate butyrate was prepared using Buchi Model B-290 Spray Drier under the following conditions.

Solution Preparation: a 3% CAB/DCM solution is left to stir overnight.

Spray Dyer Settings: Buchi B-290

Temperature: 110° C.

Aspirator: 100%

Air Flow: 600L/hr

Pump Rate: 35%

Once the inlet temperature reaches the set temperature (60° C.), the solution is fed at a 35% pump rate. Once all the solution has been dried, the final product is then collected.

Microfluidization Method

The micronized polymers can also be prepared using Microfluidics M-110P microfluidizer under the following conditions.

Solution Preparation:

0.1%-3% polymer/DI water/hydrocarbon mixture (55%-99% xylenes)/0.1% -15% (based on total volume) surfactant. (The hydrocarbon preferably has a boiling point greater than 100° C.)

Emulsion Preparation Process

a. the polymer/DI water and surfactant mixture is processed through a Ross mixer (or similar) for 3-4 minutes at low speed (500-4,000 RPM).

b. The preprocess mixture is added to a hydrocarbon. The amount of hydrocarbon is greater than the amount of DI water added. The resulting solution is once again processed in the Ross mixer for 5-8 minutes at low to moderate speed (1,000-5,000 RPM).

c. The resulting polymer/DI water/surfactant and hydrocarbon emulsion is processed 1 or more times via the microfluidics equipment to achieve the desired droplet size, this is typically accomplished in 3 passes.

d. The final stage of the process is to dry the final polymer/DI water/surfactant/hydrocarbon blend in a rotary-evaporator (or other solvent removal method, such as freeze-drying) to remove the water and hydrocarbon to produce a very fine powder. (removal of the hydrocarbon solvent is optional)

The particle size distribution of the commercial cellulose acetate butyrate and micronized cellulose acetate butyrate measured according to the method described above expressed as Sauter Mean Diameter (microns) is provided below.

Commercial cellulose acetate butyrate: 407.3 Micronized cellulose acetate butyrate 3.3

The density of the cellulose acetate butyrate before and after the micronization process measured, according to the method described above, is provided below.

Commercial cellulose acetate butyrate 1.2078 g/cm³ Micronized cellulose acetate butyrate 1.2218 g/cm³

The kinematic viscosity at 20° C. of the micronized cellulose acetate butyrate and a micronized methyl cellulose produced by spray dry method according to Examples in co-pending U.S. patent application Ser. No. 61/553582, filed Oct. 25, 2011.

Micronized methyl cellulose 2.29 cSt @ 20° C. Micronized cellulose acetate butyrate 0.71 cSt @ 20° C.

Properties of the polymers are provided in Table 6 below.

TABLE 6 Sauter Surface Zeta Mean Diameter Area Potential Density Volume Sample (microns) (m²/g) (mV) (g/cm³) (cm³) HLB MW Cellulose 407.3 0.0118 −11.8 1.2078 3.1594 17.7 9,791 acetate butyrate Micronized 3.3 1.47 −23.7 1.2218 1.4082 17.7 10,248 cellulose acetate butyrate

Examples 2-6

HFRR test was conducted according to the process described above, using the micronized polymers produced above.

FIG. 1 represent the High Frequency Reciprocating Rig (HFRR) Test concerning the wear protection of the micronized Cellulose acetate butyrate polymer (CAB Micronized) and the Non-micronized Cellulose acetate butyrate polymer (CAB Polymer) from base fuel (no polymer). The base fuel used during this test is the fuel found in Table 5. The HFRR test is conducted to determine the wear protection an additive may generate concerning the base fuel.

The treat rates for the Micronized and Non-Micronized Cellulose acetate butyrate is provided in Table 7 below. The key for below is the following: MCAB (Micronized Cellulose acetate butyrate); NMCAB (Non-Micronized Cellulose acetate butyrate).

TABLE 7 No. MCAB (wt %) NMCAB (wt %) Exp 2 0 0 Exp 3 0 0.1 Exp 4 0 0.5 Exp 5 0.1 0 Exp 6 0.5 0

The High Frequency Reciprocating Rig results of the fuel treated with Micronized and non-Micronized Cellulose acetate butyrate can be seen in FIG. 1. It can be clearly seen that the more micronized CAB used the better, smaller the wear scar with a wear scar value of 732.5 μm at 0.5 wt % micronized CAB compared to 800 μm where no micronized CAB was used. 

We claim:
 1. A composition comprising: (a) a major amount of a hydrocarbon base fluid having a viscosity of up to 600 cST at 40° C. and (b) a minor amount of a micronized cellulose acetate butyrate having a butyrate content in the range of 20 to 60 wt %, based on hydroxyl equivalent of the polymer and a number average molecular weight in the range from about 5,000 to about 50,000, and a particle size distribution on average of less than 30 microns.
 2. The composition of claim 1 wherein the amount of the micronized cellulose acetate butyrate is in the range of about 0.05 wt % to about 5 wt %, based on the composition.
 3. The composition of claim 2 wherein the micronized cellulose acetate butyrate has a particle size distribution on average of 25 microns or less.
 4. The composition of claim 2 wherein the micronized cellulose acetate butyrate have a butyrate content in the range of 30 to 55 wt %, based on hydroxyl equivalent of the polymer.
 5. A fuel composition comprising (a) a major amount of a hydrocarbon base fluid having a viscosity of up to 600 cST at 40° C. and (b) a minor amount of a micronized cellulose acetate butyrate having a butyrate content in the range of 20 to 60 wt %, based on hydroxyl equivalent of the polymer and a number average molecular weight in the range from about 5,000 to about 50,000, and a particle size distribution on average of less than 30 microns.
 6. The fuel composition of claim 5 wherein the amount of micronized cellulose acetate butyrate is in the range of 0.05 wt % to 1 wt % based on the fuel composition.
 7. The fuel composition of claim 6 wherein the micronized cellulose acetate butyrate has a particle size distribution on average of 25 microns or less.
 8. The fuel composition of claim 5 wherein the micronized cellulose acetate butyrate have a butyrate content in the range of 30 to 55 wt %, based on hydroxyl equivalent of the polymer.
 9. The fuel composition of claim 6 is a gasoline composition further comprising at least one gasoline additive.
 10. The fuel composition of claim 6 is a diesel composition further comprising at least one diesel additive.
 11. A method for reducing friction coefficient in an internal combustion engine, which comprises burning in said engine a fuel composition of claim
 6. 12. A lubricating oil composition comprising (a) a major amount of mineral and/or synthetic base oil having a viscosity of up to 600 cST at 40° C. and (b) a minor amount of a micronized cellulose acetate butyrate having a butyrate content in the range of 20 to 60 wt %, based on hydroxyl equivalent of the polymer and a number average molecular weight in the range from about 5,000 to about 50,000, and a particle size distribution on average of less than 30 microns.
 13. The lubricating oil composition of claim 12 wherein the amount of micronized cellulose acetate butyrate is in the range of 0.05 wt % to 1 wt % based on the fuel composition.
 14. The lubricating oil composition of claim 12 wherein the kinematic viscosity is in the range of 1 to 600 cSt at 40° C.
 15. The lubricating oil composition of claim 13 wherein the micronized cellulose acetate butyrate has a particle size distribution on average of 25 microns or less.
 16. The lubricating oil composition of claim 14 wherein the micronized cellulose acetate butyrate have a butyrate content in the range of 30 to 55 wt %, based on hydroxyl equivalent of the polymer.
 17. The lubricating oil composition of claim 12 further comprising at least one lubricant additive.
 18. A process for preparing a hydrocarbon fluid blend comprising: (a) providing a micronized cellulose acetate butyrate having a butyrate content in the range of 20 to 60 wt %, based on hydroxyl equivalent of the polymer and a number average molecular weight in the range from about 5,000 to about 50,000 having a particle size distribution of greater than 30 microns, in a polar organic solvent in a polymer to solvent ratio of 1:1 to 1:10 to provide a polymer-containing solution; (b) subjecting said polymer to molecular segmentation to produce a micronized polymer having a particle size distribution of less than 30 microns.; and (c) blending the micronized polymer with a hydrocarbon fluid to produce a solubilized and/or dispersed hydrocarbon fluid blend.
 19. The method of claim 18 wherein the micronized polymer has a particle size distribution of 25 microns or less.
 20. The method of claim 18 wherein the molecular segmentation is by spray drying.
 21. The method of claim 18 wherein the molecular segmentation is by microfluidization.
 22. The method of claim 18 wherein the solvent is removed from the micronized polymer.
 23. The method of claim 18 wherein the polymer is subjected to molecular segmentation to produce a micronized polymer having a particle size distribution of less than 15 microns.
 24. The method of claim 19 the micronized cellulose acetate butyrate have a butyrate content in the range of 30 to 55 wt %, based on hydroxyl equivalent of the polymer.
 25. The method of claim 18 wherein the polar organic solvent is selected from the group consisting of dichloromethane and ethanol.
 26. A micronized polymer of a cellulose acetate butyrate having a butyrate content in the range of 20 to 60 wt %, based on hydroxyl equivalent of the polymer and a number average molecular weight in the range from about 5,000 to about 50,000, and a particle size distribution on average of less than 30 microns.
 27. The micronized polymer of claim 26 wherein the micronized polymer has a particle size distribution of 25 microns or less.
 28. The micronized polymer of claim 27 have a butyrate content in the range of 30 to 55 wt %, based on hydroxyl equivalent of the polymer.
 29. The micronized polymer of claim 26 wherein the hydroxyl content of the cellulose acetate butyrate is less than 10 wt % , based on the entire polymer.
 30. The micronized polymer of claim 29 wherein the hydroxyl content of the cellulose acetate butyrate is less than 5 wt %, based on the entire polymer. 